Color measurement systems, devices, and methods

ABSTRACT

Color measurement instruments and processes provide automated and accurate color measurements. Sensor to sample distance is automatically adjusted by the instrument over the course of measurement collection. Adaptive parameters may include turntable speed, illumination spectrum, laser gain setting, number of measurement samples, duration of sampling, sample color measurement threshold, and distance variation measurement threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication No. 62/523,886, filed Jun. 23, 2017, the complete contentsof which are herein incorporated by reference.

FIELD OF THE INVENTION

The invention generally relates to color measurement and, in particular,systems, devices, and methods which improve the accuracy andreproducibility of color measurements taken from any of a variety ofsample types.

BACKGROUND

Three elements are involved in seeing or perceiving color: a lightsource, an object, and an observer. A framework of describing humancolor perception according to these three elements is sometimes referredto as the visual observing situation. To build an instrument thatquantifies human color perception, each item in the visual observingsituation may be characterized.

The first element of the visual observing situation is a light source. Alight source is a physical source of light. The visible portion of theelectromagnetic spectrum is defined by the International Commission onIllumination (CIE) as 360 to 780 nm. A plot of the relative energy ateach wavelength creates a spectral power distribution curve thatquantifies the characteristics of the light source. A CIE illuminant isa standard table of numbers representing relative energy versuswavelength for the spectral characteristics of light sources. Somecommon illuminants and their CIE abbreviations are as follows:Incandescent (A), Average Daylight (C), Noon Daylight (D₆₅), and CoolWhite Fluorescent (F2). By representing a light source as an illuminant,the spectral characteristics of the first element of the visualobserving situation is quantified and standardized.

The second element of the visual observing situation is an object.Objects modify light. Colorants such as pigments or dyes that are in oron the object selectively absorb some wavelengths of incident lightwhile reflecting or transmitting other wavelengths. The amount of lightthat is reflected, absorbed, or transmitted by the object at eachwavelength can be quantified. This can be represented as a spectralcurve. By measuring the relative reflectance or transmissioncharacteristics of an object, the second element of the visual observingsituation becomes quantified. Relative reflectance, or reflectancefactor, is defined as the relative amount of energy measured on anarbitrary sample at a fixed geometry, in reflection, with respect to aknown white sample similarly used to define the top-of-scale of themeasurement. This is important to distinguish as reflectivity is also afunction of angle and total reflectance would require a hemisphere tocollect all angles. A device which measures relative reflectance ortransmittance as a function of wavelength is typically aspectrophotometer.

The third element of the visual observing situation is the observer,which is often but not necessarily a human. A human eye has structuresreferred to as rods and cones. Cones are responsible for color visionand have three types of sensitivity: red, green, and blue. The CIEexperimentally measured the ability of the human eye to perceive color.The experimentally derived x-bar, y-bar, and z-bar functions became theCIE 1931 2° Standard Observer. The functions x-bar, y-bar, and z-barquantify the red, green, and blue cone sensitivity of an average humanobserver. An updated standard was later produced and is referred to asthe 1964 10° Standard Observer. This is the standard recommended for usetoday by the CIE.

In science and industry, the trifecta of light source, object, andobserver becomes the trifecta of light source, sample, andspectrophotometer. The CIE X, Y, and Z tristimulus color values areobtained by multiplying the illuminant, the reflectance or transmittanceof the object, and the standard observer functions. The product is thensummed for all wavelengths in the visible spectrum to give the resultingX, Y, Z tristimulus values.

A colorimetric spectrophotometer may comprise a light source, adiffraction grating, a diode array, and a processor. The instrument maybe configured to produce CIE X, Y, Z color values for a sample. Briefly,the light source illuminates the sample being measured. Light reflectedby the objects is passed to a diffraction grating which breaks it intoits spectral components. Much of the diffracted light falls onto thediode array which senses the amount of light at each wavelength. Thespectral data is sent to the processor where it is multiplied with auser-selected illuminant and observer tables to obtain CIE X, Y, Z colorvalues.

The CIE X, Y, Z value system is a color scale. When describing color,the CIE X, Y, Z values are not easily understood (they are notintuitive). Other color scales have been developed to better relate tohow humans perceive color, simplify understanding of the metrics,improve communication of color, and better represent uniform colordifferences. All colors can be organized in three dimensions: lightness,chroma or saturation, and hue. Hunter L,a,b color space is a3-dimensional rectangular color based on Opponent-Colors Theory with thefollowing dimensions:

L (lightness) axis: 0 is black, 100 is white, and 50 is middle gray

a (red-green) axis: positive values are red, negative values are green,and 0 is neutral

b (blue-yellow) axis: positive values are yellow, negative values areblue, and 0 is neutral

The opponent-colors have been explained physiologically by theorganization of cone cells into what are called receptive fields in thefovea of the human eye. A receptive field provides a number of inputsfrom the cone cells (both positive and negative) that can interface withganglion cells to produce spatial edge-detection for red-green andblue-yellow stimuli. The spectral distribution for these receptivefields correlates well with a, b.

There are two popular L,a,b color scales in use today: Hunter L,a,b andCIE L*,a*,b*. While similar in organization, a color will have differentnumerical values in these two color spaces. Both Hunter L,a,b and CIEL*,a*,b* scales are mathematically derived from CIE X,Y,Z values. Scalesof chroma and hue are also functions of a* and b*; where chroma is thescalar magnitude, ((a*)²+(b*)²)^(1/2), and hue angle is represented bythe arc tangent of (b*/a*).

Color measurement is employed in industry and in education according tocolor differences. Color differences are calculated as sample-standardvalues. According to the CIE L*,a*,b* color scale,

If delta L* is positive, the sample is lighter than the standard. Ifdelta L* is negative, the sample is darker than the standard.

If delta a* is positive, the sample is more red (or less green) than thestandard. If delta a* is negative, the sample is more green (or lessred) than the standard.

If delta b* is positive, the sample is more yellow (or less blue) thanthe standard. If delta b* is negative, the sample is more blue (or lessyellow) than the standard.

Total color difference (delta E*, or ΔE*) is based on the L*,a*,b* colordifferences and was designed to be single number metric for PASS/FAILdecisions in industry. Delta E* is determined as the square root of thesum of the squares of L*, a*, and b*:ΔE*=√{square root over ((ΔL*)²+(Δa*)²+(Δb*)²)}

Thus far color of an object or sample has been generally ascribed topigments or dyes. Other qualities of an object also play a role incolor, further complicating its measurement and characterization.Surface characteristics and geometry play an important role in color.

One surface characteristic of samples is reflectance. For opaquematerials, most of the incident light is reflected. For translucentmaterials, most of the incident light is transmitted. Reflectance maketake either of two forms. Diffuse reflection involves non-directionalreflected light. This light is scattered in many directions. Specularreflection is reflection of light by which the angle of reflectionmatches the angle of incidence of the incident light striking thesurface of the object.

Color is seen in the diffuse reflection, and gloss is seen in thespecular reflection. The reflection at the specular angle is generallythe greatest amount of light reflected at any single angle. Fromair-to-glass at low angles of incidence, specular reflection representsless than 4% of total incident light. For a 60° angle (as in glossgeometry), the reflection of polished glass is ˜10%. The remaining lightis transmitted or absorbed with almost no diffuse reflection.

Richard Sewall Hunter, a pioneer in color and appearance, identified sixvisual criteria for defining a gloss scale. These are specular gloss,contrast gloss, distinctness-of-image (DOI) gloss, absence-of-bloomgloss, sheen, and surface-uniformity gloss. In the color industry,“instrumental gloss” is the most common form of gloss measurement andcorrelates with Hunter's specular gloss criteria. The ratio of diffusereflection (45° to the angle of incidence) to specular reflection (equalto the angle of incidence) if subtracted from unity is a measure ofcontrast gloss. An exemplary geometry for measuring instrumental glosson most samples is 60° (i.e., 60/60, defined with respect to the surfacenormal of the sample). Another geometry (30/30) has combined multiplefield angles with a diode array to quantify reflection haze anddistinctness of reflected image (DORI). Correlates of a perceived glossscale in a color appearance model (CAM) may be referred to as visualgloss.

Surface texture of samples can greatly affect perceived color. Sampleswhich have exactly the same color to a spectrophotometer, but which havedifferent surface textures, will appear to have different colors to ahuman observer. Surfaces may generally be described as glossy or matte.Glossy surfaces appear darker or more saturated. Matte surfaces appearlighter and less saturated. Increased surface roughness affectsperceived color such that it appears lighter and less saturated. This iscaused by mixing diffuse reflectance (where humans see pigment color)with increased scatter from specular reflectance (white). The rougherthe surface, the greater the scatter of the specular reflectance.

Other surface characteristics such as complex spatial patterns alsoaffect perceived color. The S-CIELAB model was designed as a spatialpre-processor to the standard color difference equations, to account forthese complex color structures. This model was a first step forsimulating color appearance. Since the opponent-color spaces like L*,a*, b* are differentiable, there exists a direct correlation to thespatial receptive field and spatial gradients of the L*, a*, b* values.

Instrument geometry defines the arrangement of light source, sampleplane, and detector. There are two general categories of instrumentgeometries: Bi-directional (45°/0° or 0°/45°) and diffuse (d/8° sphere).Bi-Directional 45°/0° geometry has illumination at a 45° angle andmeasurement at 0°. The reciprocal, 0°/45° geometry, has illumination at0° and measurement at 45°. Both directional geometries by definitionexclude the specular reflection in the measurement. This is sometimesindicated in numerical tables by the phrase, “specular excluded”.Bi-Directional geometry measurements provide measurements that maycorrespond to visual changes in sample appearance due to changes ineither pigment color or surface texture. To reduce the directionality ofan arbitrary sample, the 45° illumination or detection may be revolvedcircumferentially around the sample in at least 12 equally spacedlocations.

Diffuse (sphere) geometry instruments use a white coated sphere todiffusely illuminate a sample with 8° (d/8°) viewing. Measurements on adiffuse sphere instrument can be taken with the specular included orspecular excluded. Specular included measurements negate surfacedifferences and provide values which correspond to changes in actualcolor (as opposed to perceived color). Specular excluded measurementsnegate specular reflectance on very smooth surfaces, measuring onlydiffuse reflectance. For illustration, as between two surfaces paintedwith the same red paint, one surface having a matte finish and the othersurface having a high gloss finish, the specular included measurementindicates no color difference. It quantifies only colorant differencesand negates differences in surface finishes. In the specular excludedmode, the readings quantify appearance differences, similar to thosefrom the direction (0°/45°) geometry instrument. Most diffuse geometrymeasurements are taken in the specular included mode.

Color appearance models (currently) describe qualities such aslightness, brightness, colorfulness, chroma, saturation, and hue. Theymay also be extended to include a gloss scale.

All CAMs rely on an opponent color space such as L*, a*, b*. The L*, a*,b* space, in particular, already quantifies lightness, chroma,saturation, and hue. For this reason, it is well-suited for applicationin CAM. The lightness and chroma can be scaled to provide brightness andcolorfulness.

Glossmeters, spectrophotometers, and other devices employed in opticsare traditionally independent instruments. These devices may bespecially tailored to detect and characterize very specific qualities ofthe visual observing situation (e.g., gloss, reflectance, measuredcolor, perceived color, and texture).

While specialized instruments exist for characterizing and quantifyingcolor, achieving high levels of accuracy and reproducibility isdifficult for when the instruments are subjected to use with a varietyof different sample types or with heterogeneous samples. One sample typeto the next (e.g., a cracker versus a cookie) may dramatically differentin characteristics which can affect color measurement. Within even asingle sample, properties may differ due to sample heterogeneity (e.g.,variable shape, color, and size of parts of a chocolate chip cookie, ormultiple cookies separated by aluminum space on a tray). Instruments andmethods are needed which offer adaptive parameters and operation toaccommodate sample type differences and sample differences withoutcompromising accuracy and reproducibility of the color measurements.

SUMMARY

Some exemplary embodiments of the invention are directed to colormeasurement systems, in particular non-contact color measuringspectrophotometers and processes related thereto.

Some exemplary embodiments comprise control systems and processes forautomated operation of spectrophotometers and color measuringinstruments generally. Feedback loops may be provided which changeparameters of a color measurement instrument based on real timemeasurements of distance and/or color.

Some exemplary embodiments comprise computer program instructions which,when executed by a computer such as the onboard computer of anon-contact color measuring spectrophotometer, cause the device orsystem to change one or more of sensor to sample distance, sensor tosample retention surface distance, absolute sensor position, absolutesample position, relative sensor position, relative sample position,sample movement (e.g., rotation), laser power or gain, illuminationspectrum, and other parameters of the system. Exemplary systems maycomprise one or more motors and/or controllers for adjusting one or moreof the aforementioned parameters or other parameters in response to theexecution of the computer program instructions and/or real-timemeasurements.

According to an aspect of some exemplary embodiments, a colormeasurement instrument is provided with a controller configured to makeautomated adjustments of sensor position with respect to a sample (orsample positioning with respect to the sensor). Starting from anydistance, a non-contact distance measuring device such as a lasermeasuring device directs a motorized arm to automatically adjust thesensor position with respect to the sample until a predetermined optimaldistance is obtained. Different sample heights and surfaces may resultin the system moving the sensor to different absolute sensor positions.Exemplary embodiments may continue to monitor and adjust sensor tosample distance in real time. Exemplary embodiments may minimize theeffects of uneven sample surfaces and other sources of changing sensorto sample distances which would ordinarily introduce error into colormeasurements.

According to a further aspect of some exemplary embodiments, systems andmethods are provided which monitor spectrophotometer readings in realtime. Based on changes or preconfigured triggers detected in themonitored measurements, the power of the measurement laser is increasedor decreased. For example, detection of comparatively dark samples bythe system may result in an increase in the power (gain) of the laser.Detection of comparatively light samples by the system may result in anincrease in the power (gain) of the laser.

According to yet another aspect of some exemplary embodiments, systemsand methods are provided which adjust the illumination spectrum of aspectrophotometer based on real time readings or measurements. Forexample, a system may be configured to detect low blue wavelengthreflectance and, based on the low level detected, increase the bluecomponent of the illumination spectrum (e.g., through control ofindividually regulated LEDs of an LED array of the sample illuminationsource of the spectrophotometer).

According to some exemplary embodiments, a color measurement instrumentmay comprise a sensor head comprising a color detector for collecting acolor measurement of a sample; a distance detector configured to detecta distance between the sensor head and the sample; and a motorized axisoperated with a feedback loop to automatically adjust a position of thesensor head based on the distance detected by the distance detector. Themotorized axis may be configured to adjust the distance entirelyindependent of human intervention. The distance detector and motorizedaxis may be configured to continually monitor and adjust the distance ofthe sensor head to the sample in real time so as to minimize effects ofuneven sample surfaces as a source of changing sensor head to sampledistance. The instrument may further comprise a turntable configured forrotation of the sample concurrent with the continual monitoring andadjustment of sensor head to sample distance. The instrument may furthercomprise an LED array for emitting electromagnetic radiation detectableby the color detector as a reflectance of the sample, and one or morelasers for emitting electromagnetic radiation detectable by the distancedetector when reflected from the sample. The instrument may furthercomprise one or more of an onboard computer, a signal conversion module,and a spectrometer system which comprise one or more processorsconfigured to perform signal processing of the signals received from thedistance detector and color detector. The one or more lasers may beconfigured with variable gain, and the one or more processors areconfigured to increase or decrease real time gain of the one or morelasers based on changes in sample darkness or lightness. The LED arraymay be configured with an adjustable illumination spectrum, and the oneor more processors may be configured to adjust the illumination spectrumof the LED array based on color measurements of the color detector. Oneor more distance measurements from the distance detector and one or morereflectance measurements from the color detector may be acquired andstored in data pairs by the one or more processors. At least one of theone or more of onboard computer, signal conversion module, andspectrometer system may be configured to adaptively adjust one or moreof turntable speed, illumination spectrum, laser gain setting, number ofmeasurement samples, duration of sampling, sample color measurementthreshold, and distance variation measurement threshold.

According to some exemplary embodiments, a method of performingnon-contact color measurements may comprise collecting a colormeasurement of a sample with a color detector of a sensor head;detecting a distance between the sensor head and the sample with adistance detector; and operating a motorized axis with a feedback loopto automatically adjust a position of the sensor head based on thedistance detected by the distance detector. Adjusting of the distance bythe motorized axis may be entirely independent of human intervention.The method may comprise continually monitoring and adjusting thedistance of the sensor head to the sample in real time with the distancedetector and motorized axis so as to minimize effects of uneven samplesurfaces as a source of changing sensor head to sample distance. Themethod may comprise rotating the sample with a turntable concurrent withthe continual monitoring and adjustment of sensor head to sampledistance. The method may comprise, with an LED array, emittingelectromagnetic radiation detectable by the color detector as areflectance of the sample, and, with one or more lasers, emittingelectromagnetic radiation detectable by the distance detector whenreflected from the sample. The method may comprise signal processing ofthe signals received from the distance detector and color detector withone or more processors of one or more of an onboard computer, a signalconversion module, and a spectrometer system. The method may compriseincreasing or decreasing real time gain of the one or more lasers basedon changes in sample darkness or lightness. The method may compriseadjusting the illumination spectrum of the LED array based on colormeasurements of the color detector. The method may comprise acquiringand storing by the one or more processors one or more distancemeasurements from the distance detector and one or more reflectancemeasurements from the color detector in data pairs. The method maycomprise adaptively adjusting one or more of turntable speed,illumination spectrum, laser gain setting, number of measurementsamples, duration of sampling, sample color measurement threshold, anddistance variation measurement threshold with at least one of the one ormore of onboard computer, signal conversion module, and spectrometersystem.

According to some exemplary embodiments, a non-transitory computerreadable storage medium may comprise computer program instructionswhich, when executed by one or more processors of one or more of anonboard computer, signal processing module, and spectrometer system of anon-contact color measurement instrument, cause the instrument toperform collecting a color measurement of a sample with a color detectorof a sensor head; detecting a distance between the sensor head and thesample with a distance detector; and operating a motorized axis with afeedback loop to automatically adjust a position of the sensor headbased on the distance detected by the distance detector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a color measurement device at a first distance position.

FIG. 2 is the color measurement device at a second distance position.

FIG. 3 is the color measurement device with a calibration unit attached.

FIGS. 4A and 4B are the color measurement device with external housingand user interface removed from the sensor module for view of deviceinternals.

FIG. 5 is another view of the sensor module internals.

FIG. 6 is a side profile of the color measurement device showing itsadjustable spatial axes.

FIG. 7A is the color measurement device's motorized axis at a firstposition.

FIG. 7B is the color measurement device's motorized axis at a secondposition.

FIGS. 8A and 8B are the color measurement device with housing removed toshow internals of the motorized axis.

FIG. 9 is a block diagram of the color measurement device feedback loop.

FIG. 10A is the color measurement device with a bottom housing portionremoved to show an onboard computer.

FIG. 10B is a close-up of the color measurement device with visibilityof the onboard computer.

FIG. 11 is an exemplary method for taking color measurements.

FIG. 12 is an exemplary subroutine to the first stage of the method ofFIG. 11.

FIG. 13 is an exemplary subroutine to the second stage of the method ofFIG. 11.

FIG. 14 is an exemplary subroutine to the third stage of the method ofFIG. 11.

DETAILED DESCRIPTION

FIG. 1 shows an exemplary color measurement device 100 (e.g.,instrument). The device 100 comprises a surface 101 for arrangingsamples (e.g., of a rotating sample turntable 102). The device 100further comprises a sensor module 103 that includes a sensor userinterface 104 and a sensor head 105. Note that in some of thedescriptions herein “sensor” may be used to refer to “sensor head”. Thesensor module 103 is set at a distance 106 from the sample turntable 102by a movable (e.g., motorized) vertical axis 107. The sensor module 103may be moved to any distance within a range of distances from the sampleturntable 102.

FIG. 2 shows the color measurement device 100 of FIG. 1 after anadjustment in the position of the sensor module 103. The sensor module103 is shown in a lower position (e.g., at a closer distance 106′ to anysample placed on the sample turntable 102).

The decision as between a device configuration at distance 106 (FIG. 1),a distance 106′ (FIG. 2), or some other distance within the operatingrange of the device 100 is dependent upon the sample to be measured. Thedevice 100 is configured as a multi-application device automaticallyadaptive and adjustable to collect accurate color measurements for anyof a wide variety of samples that may be arranged on the surface 101,and to automatically adjust to collect accurate color measurements forselective parts of whole samples.

Just a few non-limiting examples of samples for which color measurementsmay be taken are food items like saltine crackers, bagels, and chocolatechip cookies. Non-food samples are of course also usable, but food isexemplary as an industry where color measurement is common. It may bereadily appreciated to a reader of this disclosure that a cracker, abagel, and a chocolate chip cookie may have considerably differentdimensions (e.g., heights or thicknesses). However even for any one ofthese samples the distance from a sensor head 105 to the surface of thesample may vary considerably depending on the point on the surface ofthe sample from which measurements are taken. A saltine cracker variesin thickness due to salt crystals and blisters, for example. A bagelvaries in thickness from zero thickness (at the hole in the center) to apositive thickness which varies with each increment in the bagel'sradial direction. A chocolate chip cookie varies in thickness based onthe presence or absence of a chocolate chip at any given point on thecookie's surface. Moreover, for any samples with multiple constituentparts in the sample (e.g., salt crystals and cracker body; raisins inbagel bread; chips in cookie dough), it may be desired or required tocollect color measurements of only one constituent part to the exclusionof the other parts. An exemplary instrument 100 provides adaptability tothese requirements.

FIG. 3 shows the sensor module 103 with a calibration unit 301 attached.The calibration unit may magnetically attach to the sensor housing or beattached by other means. The calibration unit 301 enables the insertionof special calibration tiles at a known distance to set the bottom andtop of the Grayscale for the instrument 100. The direct attachment ofthe calibration unit 301 to the sensor head 105 is advantageous in thatit eliminates any effect of the position of the moveable vertical axis107. In other words, regardless of the distance 106, 106′, etc. betweenthe sensor head 103 and the sample or turntable 102, the distancebetween the sensor head 103 and a calibration tile remains constant.

FIG. 4A shows a cover of the sensor module 103 (including the userinterface 104) removed to permit a view of the optical components withinthe sensor module housing.

FIG. 4B is a close up of the sensor module internals. The sensor module103 comprises a signal conversion module/system 401, a distance detector402, an illumination source 403 (e.g., comprising an LED array and/orone or more lasers), a color detector 404, and spectrometer system 405.The color detector 404 collects signal reflected from the sample andpasses it via fiber optic bundles to the spectrometer 405 forcharacterization. The detectors 402 and 404 may together constitute thesensor head 105. The sensor head 105 may also comprise the illuminationsource 403 and the optical window 406. The sensor head 105 may alsocomprise housing.

Some electromagnetic radiation emitted from the illumination source 503may reflect off a sample, the reflected light being received by thedistance detector 502. Other electromagnetic radiation emitted from theillumination source may reflect off the sample, the reflected lightbeing received by the color detector 504. For example, the illuminationsystem may comprise a laser for use together with the distance detectorand an LED array for use with the color detector 504 and spectrometersystem 505.

FIG. 5 is another close up of internals of the sensor module 103. Lenses502, 503, and 504 of the distance detector 402, illumination source 403,and color detector 404 are visible, respectively. The signal conversionmodule 401 (i.e., signal processing module) and spectrometer system 405are configured to perform signal processing of the signals received fromthe distance detector 402 and/or color detector 404. A fiber optic cable506 transfers signals from the color detector 404 to the spectrometersystem 405. A second fiber optic cable 507 transfers a reference signalfrom the illumination source 403 to the spectrometer system 405.

FIG. 6 is a side profile of the color measurement device 100 showing thedevice's adjustable spatial axes. An exemplary device 100 mayautomatically and adaptively adjust positioning according to one or morespatial degrees of freedom. In the illustrated embodiment the device 700is configured for adjustment of the position of sensor head 105 alongtranslational direction 701 (here, the vertical direction) andtranslational direction 702 (here, the horizontal direction). Arrow 703indicates a direction of rotation of the turntable 102 which is alsocontrollable by the device 100. In alternative embodiments the surface101 for receiving the sample may be moveable while a sensor or sensorhead remains stationary (or also moves). In any case, separationdistances such as the distance 106 may be automatically adjustablebefore and during measurement protocols under the semi-autonomous orfully-autonomous control of the device 100.

FIG. 7A shows a rear facing view of the device 100. The movable axis 107comprises one or more motors which allow motorized control of the sensorhead's vertical position. FIG. 7B is a rear facing view of the device100 after the sensor head 105 has moved to a lower position on themoveable axis 107 (which may be alternatively referred to as an arm ofthe device). In the device 100 illustrated by the figures, the verticalaxis 107 is substantially parallel with a gravity vector, assuming thedevice 100 is arranged on a tabletop or similarly flat environmentalsurface. Indeed, the tabletop configuration of the device 100 is oneadvantage aspect of this embodiment. It should be appreciated, however,that alternative embodiments of the invention may assume alternationpositions with respect to the environment such that the axis separatingthe sensor head 105 and the surface 101 for arranging samples is notnecessarily vertical. The axis may instead be horizontal or at somenon-orthogonal angle between vertical and horizontal, for example. Ingeneral, the movable axis 107 is normal to the plane of the surface 101.

In some embodiments like device 100 a second movable axis is included.The second moveable axis 127 may be motorized or manual. The secondmoveable axis 127 is configured to change the point on the surface 101above which the sensor head 105 is centered. Generally, the secondmoveable axis 127 may not require any adjustments while colormeasurements are in progress for a given sample. In contrast, aplurality of adjustments in the moveable axis 107 may be necessary whilemeasuring the given sample.

FIGS. 8A and 8B show the motorized axis 107 with housing removed topermit a view of internal components. An exemplary motorized axis 107may comprise one or more motors 810 (e.g., a stepper motor) and adedicated rotary position feedback device or encoder 812. The motorizedaxis 107 may further comprise a mobile stage assembly 814 whichtranslates along a guide rail(s) 811 by rotary motion of the motorizedlead screw 813 through the nut 815 rigidly attached to the mobile stageassembly 814. The motorized axis may comprise a gear assembly, e.g., inthe mobile stage assembly and/or in the motor assembly. The motorizedaxis 107 may further comprise other mechanical elements such as abearing 816.

FIG. 9 is a block diagram of a feedback loop 900 for adaptivelyadjusting the relative distance between sensors and sample. The sensorhead 105 comprises the distance detector 402 configured to detectdistance between the sensor head 105 and the sample. The sensor head 105further comprises the color detector 404 for collecting colormeasurements of the sample. The motorized axis 107 comprises one or moremotors 810 and a translation assembly 911 (generally comprising themobile stage assembly 814, guide rails 811 and lead screw 813 accordingto the exemplary embodiment depicted in FIGS. 8A and 8B). The motorizedaxis may also comprise a dedicated encoder 812, e.g., as is common inprecision actuators like servomotors. The motorized axis 107 operateswith a feedback loop to automatically adjust the distance between thesensor head 105 and the sample based on the distance detected by thedistance detector 402. One or more processors 908 may be involved insignal conversion and transmission between the distance detector 105 andmotorized axis 107. Distance measures may be obtained by the distancedetector 402 and changes in distance effected by the motorized axis 107in a continual loop, regulated by the one or more processors 908 (e.g.,as described below). Adjusting the distance may be implemented byadjusting a position of the sensor head, adjusting a position of thesample, or both.

FIG. 10A shows a view of the device 100 with a bottom housing portionremoved to permit visibility of an onboard computer 1001. The computeris communicatively coupled (e.g., by a wired or wireless connection) tothe signal conversion/signal processing module 401 and the spectrometersystem 405. The computer 1001 comprises one or more processorsconfigured for executing computer program instructions in accordancewith the teachings herein. Processing described herein may be dividedamong the computer 1001, the signal processing module 401, and thespectrometer system 405.

FIG. 10B shows a close up of the bottom of the device with a view of theonboard computer. The onboard computer may comprise and/or be connectedwith one or more storage media (shown generally at 1002) andinput/output devices (shown generally at 1003). The storage media 1002may comprise instructions for execution by the one or more processors.

One or more of the onboard computer 1001, the signal processing module401, and the spectrometer system 405 may be configured to perform anyone or combination of the following:

-   -   adjust a height/position/location/distance of the sensors/sensor        module based on the real time distance detected between the        sensors and a surface of a sample below the sensors,    -   adjust a power or gain of a light emitting component based on        (e.g., in dependence on) real time or substantially real time        distance or sample readings as detected by one or more of the        detectors and processed by the signal processing system and/or        the spectrometer system,    -   adjust the illumination spectrum of the illumination system        based on (e.g., in dependence on) real time or substantially        real time reflectance measurements detected by the color        detector.

The adjustments may be semi-autonomous or fully autonomous. Theadjustments may be made entirely independent of user/human intervention.Sampling and adjustments during sampling may be conducted with partialautomation or full automation. Adjustments in distance/location of thesensor module may be continuous during part up to an entirety of asample measurement period. The adjustments may be made to counteract anydeviations from a preset or predetermined optimal distance. Theadjustments may serve to maintain a constant distance. Adjustments inheight of the sensor module may occur whenever one or more othervariables change during the measurement period. For example, an ongoingfeedback loop may exist between the motorized vertical axis and thedistance detector, facilitated/managed by the signal processing moduleand/or the onboard computer.

FIGS. 11 to 14 depict a method 1100 and subprocesses thereof forcollecting color measurements according to an exemplary embodiment.Generally, as shown in FIG. 11, method 1100 may be described accordingto three stages of activity: optimizing sensor position (block 1110),configuring measurement parameters (block 1120), and optimizing samplemeasurement (block 1130). The following explanations of method 1100 mayrefer to various components of the color measurement device 100illustrated by the preceding figures. Device 100 is an exemplaryphysical embodiment for performance of exemplary method 1100. Otherdevices and systems may also be used, as may alternative methods.

FIG. 12 shows the subprocess 1110 for optimizing sensor position. Thesubprocess 1110 may start with sample rotation at block 1111. After thesample to be measured is arranged at the surface 101, a user (e.g., ahuman employing a color measurement device 100 to characterize a sample)initiates the measurement process via the user interface 104 and theturntable 102 supporting the sample is directed to begin rotation at adefault predetermined speed. Note that in some embodiments some samplesmay not be subject to rotation.

The sensor head 105 begins to move at block 1112 until the sample iswithin a predetermined distance range as detected by the distancedetector 402. Block 1112 may start with the sensor head 105 at an upperor maximum limit of sensor-to-sample distance and incrementally reducethe distance by moving the sensor head 105 while taking a series ofdistance measurements with the distance detector 402. At too great ofdistances the distance detector 1112 may collect zero, negligible, orsub-predetermined threshold levels of reflected laser signal from theillumination source 403. Block 1112 may continue (e.g., the sensor head105 may continue to gradually or incrementally approach the sample)until the amount of reflectance from the one or more lasers ofillumination source 403 exceeds some predetermined threshold. Block 1112serves to move the sensor head 105 until it is able to “see” the sample.

With the sensor head 105 now able to see the sample, the strength ofreflected signal from the distance laser is used to determine optimumlaser gain setting at block 1113. The optimum laser gain setting may bea function of one or more surface properties of the sample, such as thetexture or gloss.

The distance adjustments of block 1112 and the laser gain adjustments1113 may be interrelated or interdependent. Block 1114 is a routine ofoptimizing both parameters in tandem. The device 100 may continueacquiring successive distance reflectance data pairs while changing thesensor-to-sample distance (e.g., while reducing the sensor-to-sampledistance; while moving the sensor head toward the sample). In otherwords, according to the organization structure of the flowchart in FIG.12, block 1114 constitutes a concurrent repetition of blocks 1112 and1113. The culmination of blocks 1112 to 1114 is block 1115, at which thedevice 100 reaches an optimized measurement position. At block 1115 thesensor head 105 may (temporarily) stop moving and store referencelocation (of the sensor head 105) used in subsequent data collection. Atthe end of 1110, the sensor (head) is located in the optimum positionfor the loaded sample. The laser gain is also set, and that parametermay be used for subsequent stages and steps.

Method 1100 continues from stage 1110 to stage 1120, shown in FIG. 13.Stage 1120 comprises configuring measurement parameters. A moving sampleis profiled at block 1121. This may entail rotating the sample on theturntable 102 for one full rotation or a plurality of rotationsdepending on a user-determined setting (e.g., 1, 2, 3, 4, 5 or more, 10or more, etc. rotations). Using predetermined data collection parametersfrom stage 1110 (e.g., the set laser gain), sequential distance andreflectance data pairs are collected for the full rotation of thesample. The distance data is collected with the distance detector 402.Concurrently, reflectance data (in particular spectral, i.e., colordata) is collected with the color detector 404. A single rotation mayyield a plurality (e.g., 30, 40, 50, 60, or more) data pairs, forexample, which altogether may be stored as a sample “profile”.Collecting the distance and reflectance data in pairs permits subsequentapplication of the distance data to correct output color data. In someembodiments distance and reflectance are always collected in pairs.

Next, sample data analysis is performed at block 1122. The criteriaprocessed may be an ordered sequence of one or more (e.g., all) of thefollowing: sample presentation orientation, sample shape/structuralcharacteristics, sample surface and height variability, discrete orcontinuous nature of the sample, spectral reflectance characteristicsincluding normality and distribution of color properties, sampledistance rejection frequency, and identification of non-colorattributable properties.

Sample presentation orientation refers to samples such as potato chipsthat may be lying flat in the sample pan or on edge or some position inbetween. Sample shape characteristics may include, for example, smalldonut-style cereals that have a center hole or unique extruded shapessuch as cheese curls. Sample height variation is represented by thecurvature of a muffin top or loaf of bread, for example. A discretesample is one characterized by a placement of some countable number ofsimilar products that are positioned such that they do not overlap orcreate a contiguous sample pattern, for example an array of sugarcookies or snack wafers in a pan. In contract, a continuous sample istypically comprised of countless smaller samples that are measured inbulk by dumping them into a sample pan, e.g. beans, coffee ground,pellets, or granules. The normality and distribution of spectralreflectance characteristics are useful in identifying samples that havenon-homogenous color distributions, e.g. a chocolate chip cookie orblueberry muffin both of which have a base color and highlights that aredetectable. A sample distance rejection occurs when the heightmeasurement of a sample, typically a discrete one, varies beyond therange of interest of the sample, indicating that the sample is no longerin view of the sensor or that the height/distance signal is not usable.A non-color attributable property is one that is not directly related tothe sample color properties of interest, for example, the color of thepan containing the samples.

Next, optimum measurement parameters are determined at block 1123.Adaptive parameters and control points may include one or more (e.g.,all) of the following: turntable speed, illumination spectrum and gainsettings, number of measurement samples (duration), and sample color anddistance variation thresholds. These parameters and control points are“adaptive” in that the device 100 is configured to select and adjustvalue(s) for one or more of the parameters or control points based onthe immediate sample to be measured. The actual values assumed for theparameters and control points are adapted to accommodate the potentiallyunique or particular qualities of a given sample. As between two sampleswhich are different (e.g., a potato chip and a slice of bread) theadaptive parameters and control points may take different values inaccordance with exemplary color measurement methods (e.g., method 1100).

At stage 1130, and in particular at block 1131, the device 100 executesthe prescribed measurement protocol determined at stage 1120. Themeasurement protocol has been adapted to the present sample or sampletype and thus uses the adaptive measurement configuration and parametersdetermined in stage 1120. The raw data produced by the measurementprocess of the device 100 may be stored and/or output to a user. In manycases users may require only some of the available data generated. Atblock 1132, measurement results are output to a user. Simplified colormeasurement results may be reported while metadata containing alldetails of the applied adaptive measurement parameters are stored foroptional use.

A difference between the two stages 1120 and 1130 is that stage 1120 ismeasuring, studying, and analyzing the sample that is presented to theinstrument. Once the “profile” is collected and analyzed, the instrumentis configured a certain way to then take an optimized measurement atstage 1130. The parameters of block 1123 are used in block 1131 wherethe final data is collected and the answer computed and then presentedat block 1132.

The sensor at stage 1130 is executing the optimum measurement of theexact presented sample. For example, the sample presented at step 1111is the same sample, untouched or disturbed, at the time of the finalmeasurement at step 1131. As an illustrative example, one may imagine atray of tortilla chips. The chips are laid out in a specific random way,and the instrument profile will be trained upon the details of thatsample in that exact configuration. If a user were to rake her handthrough the chips and re-level it or shake it up, this disturbance wouldhave the effect of creating a new sample in actuality.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor (or processors) to carryout aspects of the present invention.

A computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java, Smalltalk, C++ or the like,and conventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on a standalonespecial purpose instrument like device 100, on a user's computer, partlyon the user's computer, as a stand-alone software package, partly on theuser's computer and partly on a remote computer or entirely on theremote computer or server. In the latter scenario, the remote computermay be connected to the user's computer through any type of network,including a local area network (LAN) or a wide area network (WAN), orthe connection may be made to an external computer (for example, throughthe Internet using an Internet Service Provider). In some embodiments,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGA), or programmable logicarrays (PLA) may execute the computer readable program instructions byutilizing state information of the computer readable programinstructions to personalize the electronic circuitry, in order toperform aspects of the present invention.

Some aspects of the present invention are described herein withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems), and computer program products according toembodiments of the invention. It will be understood that each block ofthe flowchart illustrations and/or block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer readable program instructions. In addition,while a general logic flow has been illustrated (e.g., in FIGS. 11-14),is not necessary in all embodiments that all blocks are performed orthat the blocks are performed in the illustrated order. Some steps mayoccur in a different order than illustrated. In some embodiments somesteps may be omitted or have other intervening steps added. In someembodiments some steps may be performed concurrently. In someembodiments some steps may be performed just once or a plurality oftimes.

Computer readable program instructions may be provided to a processor ofa general purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Other embodiments of the invention may comprise additional featuresbeyond those described in connection with the illustrative embodimentdepicted in the figures. Furthermore, other embodiments may comprisefewer than the described features. That is to say, some embodiments maycomprise or consist of a subset of the features of the exemplary deviceshown in the figures. Variations and alternative configurations mayoccur in the practice of the invention.

What is claimed is:
 1. A method of performing non-contact colormeasurements with a color measurement instrument, comprising collectingone or more preliminary measurements of a specific sample with the colormeasurement instrument, at least one of the preliminary measurementsbeing performed using a default setting; adapting the color measurementinstrument to the specific sample by automatically adjusting one or moremeasurement parameters or control points of the color measurementinstrument based on the one or more preliminary measurements; andcollecting one or more final measurements of the specific sample usingthe adaptively adjusted measurement parameters or control points.
 2. Themethod of claim 1, wherein the collection of the one or more finalmeasurements of the specific sample is performed prior to any touchingor disturbing of the specific sample since the collection of the one ormore preliminary measurements.
 3. The method of claim 1, wherein theadaptively adjusted measurement parameters or control points include oneor more of turntable speed, illumination spectrum, laser gain setting,number of measurement samples, and duration of sampling.
 4. The methodof claim 1, wherein the adaptively adjusted measurement parameters orcontrol points include one or more of sample color measurement thresholdand distance variation measurement threshold.
 5. The method of claim 1,wherein the preliminary measurements and final measurements both includereflectance.
 6. The method of claim 5, wherein the adapting stepcomprises adjusting sensor-to-sample distance, and adjusting laser gainbased on reflected laser signal.
 7. The method of claim 6, wherein thesensor-to-sample distance adjustments and laser gain adjustments areperformed in tandem.
 8. The method of claim 1, further comprisingrotating the specific sample concurrently with data collection; andproducing a sample profile by collecting a plurality of distance,reflectance data pairs for a full rotation of the sample.
 9. The methodof claim 8, wherein the adapting step comprises adaptive adjustment ofone or more of the following parameters or control points after theproduction of the sample profile: turntable speed, illuminationspectrum, laser gain setting, number of measurement samples, andduration of sampling.
 10. The method of claim 8, wherein the adaptingstep comprises adaptive adjustment of one or more of sample colormeasurement threshold and distance variation measurement threshold. 11.The method of claim 1, further comprising increasing or decreasing realtime gain of one or more lasers used for determination of distance insupport of the collection of color measurements based on changes indarkness or lightness of the specific sample.
 12. The method of claim 1,wherein the adapting step comprises continually monitoring and adjustinga sensor-to-sample distance in real time so as to minimize effects ofuneven sample surfaces as a source of changing sensor-to-sampledistance.
 13. The method of claim 1, further comprising adjusting anillumination spectrum of an LED array used for the collection of the oneor more final measurements based on the preliminary measurements.
 14. Acolor measurement instrument for performing non-contact colormeasurements, comprising a sensor head for collecting preliminarymeasurements and final measurements; one or more processors configuredfor collecting one or more preliminary measurements of a specific samplewith the sensor head, at least one of the preliminary measurements beingperformed using a default setting; adapting the color measurementinstrument to the specific sample by automatically adjusting one or moremeasurement parameters or control points of the color measurementinstrument based on the one or more preliminary measurements; andcollecting one or more final measurements of the specific sample withthe sensor head using the adaptively adjusted measurement parameters orcontrol points.
 15. The color measurement instrument of claim 14,wherein the collection of the one or more final measurements of thespecific sample is performed prior to any touching or disturbing of thespecific sample since the collection of the one or more preliminarymeasurements.
 16. The color measurement instrument of claim 14, whereinthe adaptively adjusted measurement parameters or control points includeone or more of turntable speed, illumination spectrum, laser gainsetting, number of measurement samples, and duration of sampling. 17.The color measurement instrument of claim 14, wherein the adaptivelyadjusted measurement parameters or control points include one or more ofsample color measurement threshold and distance variation measurementthreshold.
 18. The color measurement instrument of claim 14, wherein theadapting step comprises adjusting sensor-to-sample distance, andadjusting laser gain based on reflected laser signal, wherein thesensor-to-sample distance adjustments and laser gain adjustments areperformed in tandem.
 19. The color measurement instrument of claim 14,wherein the one or more processors are further configured for adjustingan illumination spectrum of an LED array used for the collection of theone or more final measurements based on the preliminary measurements.20. A non-transitory computer readable storage medium comprisingcomputer program instructions which, when executed by one or moreprocessors of one or more of an onboard computer, signal processingmodule, and spectrometer system of a non-contact color measurementinstrument, cause the instrument to perform collecting one or morepreliminary measurements of a specific sample with a sensor head, atleast one of the preliminary measurements being performed using adefault setting; adapting the color measurement instrument to thespecific sample by automatically adjusting one or more measurementparameters or control points of the color measurement instrument basedon the one or more preliminary measurements; and collecting one or morefinal measurements of the specific sample with the sensor head using theadaptively adjusted measurement parameters or control points.